The present invention relates to thermoplastic resin compositions which are reduced in the formation of a gel (crosslinked polymer) due to a block copolymer crosslinking reaction during molding, are reduced in melt viscosity change due to crosslinking and cleavage of block copolymer chains, and are excellent in suitability for film or sheet forming and suitability for injection molding, and to an asphalt composition which is excellent in high-temperature storage stability and low-temperature characteristics and has an excellent balance among properties. More particularly, the invention relates to resin compositions comprising a specific block copolymer comprising a vinylaromatic hydrocarbon, isoprene and 1,3-butadiene, and at least one thermoplastic resin selected from styrene resins, polyolefin resins and poly(phenylene ether) resins, and to an asphalt composition comprising a block copolymer of a specific structure comprising a vinylaromatic hydrocarbon, isoprene and 1,3-butadiene, and an asphalt.
Block copolymers comprising a conjugated diene and a vinylaromatic hydrocarbon have satisfactory compatibility with resins such as polystyrene and are advantageously used for improving the impact resistance of these resins.
For example, JP-B-45-19388 and JP-B-47-43618 describe the use of a linear block copolymer or a branched block copolymer as an impact modifier for polystyrene.
On the other hand, it has been attempted to incorporate an olefin resin for the purpose of improving the oil resistance of styrene resins. However, since styrene resins have poor compatibility with olefin resins, there has been a problem that the incorporation results in a composition which suffers a separation phenomenon and has poor mechanical strength. A composition comprising a polyolefin resin and a polystyrene resin and containing a hydrogenated block copolymer has hence been proposed in, e.g., JP-A-56-38338.
Poly(phenylene ether) resins are excellent in mechanical properties, electrical properties, etc. and are extensively used as business apparatus housings, various industrial parts, and the like. Especially for use in applications such as business apparatus and acoustic appliances, where damping performance is required, a poly(phenylene ether) resin composition containing a block copolymer in which the content of 3,4-bonds and 1,2-bonds (vinyl bonds) in the diene units is 40% or higher is disclosed in, e.g., JP-A-3-181552.
Poly(phenylene ether) resins are inferior in oil resistance and impact resistance, and it has been attempted to incorporate an olefin resin in order to improve these properties. However, since these two kinds of resins have poor compatibility, the incorporation has posed a problem that a separation phenomenon occurs. A composition comprising a polypropylene resin and poly(phenylene ether) and containing a hydrogenated block copolymer has hence been proposed in, e.g., JP-A-9-12800.
On the other hand, asphalt compositions are extensively used in applications such as road paving, waterproof sheets, sound insulation sheets, and roofing. Many attempts have been made to improve properties of asphalts for such applications by adding various polymers thereto. For example, JP-B-47-17319 discloses an asphalt composition containing a block copolymer of a vinylaromatic compound and a conjugated diene compound. Furthermore, JP-A-54-57524 discloses an asphalt composition containing a radial teleblock copolymer.
An object of the invention is to provide a resin composition which comprises a block copolymer and a polystyrene resin and/or poly(phenylene ether) resin and which is reduced in gel formation due to a block copolymer crosslinking reaction during molding, is reduced in melt viscosity change due to crosslinking and cleavage of block copolymer chains, and has satisfactory low-temperature impact resistance and excellent suitability for film or sheet forming and injection molding. Another object of the invention is to provide a resin composition which comprises a block copolymer and a polyolefin resin, polystyrene resin, and/or poly(phenylene ether) resin and which has improved impact resistance besides those properties.
A still other object of the invention is to provide an asphalt composition which contains a specific block copolymer comprising a vinylaromatic hydrocarbon and a conjugated diene and which has an excellent balance among properties such as softening point, strength, and workability, is excellent in high-temperature storage stability and low-temperature characteristics, and is suitable for use in road paving applications, roofing/waterproof sheet applications, sealant applications, and the like.
It was found that use of a thermoplastic resin selected from styrene resins, polyolefin resins, and poly(phenylene ether) resins in combination with a block copolymer comprising a vinylaromatic hydrocarbon, isoprene, and 1,3-butadiene and having a specific polymer structure is effective in reducing the gel formation due to a block copolymer crosslinking reaction during molding to thereby considerably reduce the gel level (fish eyes) and in simultaneously reducing the melt viscosity change due to crosslinking and cleavage of block copolymer chains and attaining excellent low-temperature impact resistance, etc. It was also found that in a composition comprising a combination of a thermoplastic resin selected from styrene resins, polyolefin resins, and poly(phenylene ether) resins with a specific hydrogenated block copolymer and a block copolymer comprising a vinylaromatic hydrocarbon, isoprene and 1,3-butadiene and having a specific polymer structure, the specific hydrogenated block copolymer improves the compatibility of the styrene resin and/or poly(phenylene ether) resin with the polyolefin resin, while the block copolymer comprising a vinylaromatic hydrocarbon, isoprene, and 1,3-butadiene and having a specific polymer structure blends preferentially with the styrene resin and/or poly(phenylene ether) resin to form a homogeneous mixture and thereby improve impact resistance. The invention has been completed based on these findings.
On the other hand, extensive investigations were made on property improvements in compositions which comprise an asphalt and a block copolymer comprising a vinylaromatic hydrocarbon and a conjugated diene and are to be used in road paving applications, roofing/waterproof sheet applications, sealant applications, or the like. As a result, it was found that an asphalt composition which comprises an asphalt and a block copolymer comprising a vinylaromatic hydrocarbon and conjugated dienes and are excellent in high-temperature storage stability and low-temperature characteristics is obtained by using isoprene and 1,3-butadiene as the conjugated dienes in a proportion within a specific range and so as to result in a specific vinyl bond amount. The invention has been thus completed.
Namely, the invention relates to the following compositions.
(1) A composition comprising:
(A) from 2 to 40 parts by weight of a block copolymer which is a block copolymer having at least two polymer blocks mainly comprising a vinylaromatic hydrocarbon and further having at least one copolymer block comprising isoprene and 1,3-butadiene and/or at least one copolymer block comprising isoprene, 1,3-butadiene and a vinylaromatic hydrocarbon, the block copolymer having a vinylaromatic hydrocarbon content of from 5% by weight to less than 60% by weight and a total content of isoprene and 1,3-butadiene of from more than 40% by weight to 95% by weight, and the block copolymer having an isoprene/1,3butadiene weight ratio in the range of from 95/5 to 5/95, a vinyl bond amount less than 40% by weight, and a number-average molecular weight in the range of from 30,000 to 500,000; and
(B) from 98 to 60 parts by weight of either at least one thermoplastic resin selected from styrene resins, polyolefin resins, and poly(phenylene ether) resins or an asphalt.
(2) A resin composition obtained by compounding 100 parts by weight of a resin composition comprising:
(A) from 2 to 40 parts by weight of a block copolymer which is a block copolymer having at least two polymer blocks mainly comprising a vinylaromatic hydrocarbon and further having at least one copolymer block comprising isoprene and 1,3-butadiene and/or at least one copolymer block comprising isoprene, 1,3-butadiene and a vinylaromatic hydrocarbon, the block copolymer having a vinylaromatic hydrocarbon content of from 5% by weight to less than 60% by weight and a total content of isoprene and 1,3-butadiene of from more than 40% by weight to 95% by weight, and the block copolymer having an isoprene/1,3butadiene weight ratio in the range of from 95/5 to 5/95, a vinyl bond amount less than 40% by weight, and a number-average molecular weight in the range of from 30,000 to 500,000; and
(B) from 98 to 60 parts by weight of at least one thermoplastic resin selected from styrene resins, polyolefin resins, and poly(phenylene ether) resins, with
(C) from 2 to 30 parts by weight of a hydrogenated block copolymer comprising a vinylaromatic hydrocarbon and a conjugated diene and having a vinylaromatic hydrocarbon content of from 5 to 90% by weight and a degree of hydrogenation of 20% or higher.
The invention will be explained below in detail.
The block copolymer to be used as ingredient (A) in the invention is obtained by polymerizing a vinylaromatic hydrocarbon with isoprene and 1,3-butadiene in an organic solvent using an organolithium compound as an initiator.
Examples of hydrocarbon solvents for use in producing the block copolymer include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, and isooctane, alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane, aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene, and the like. These may be used either alone or as a mixture of two or more thereof. Examples of the vinylaromatic hydrocarbon to be used for the block copolymer include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, xcex1-methylstyrene, vinylnaphthalene, vinylanthracene, 1,1-diphenylethylene, and the like. However, especially general ones include styrene. These may be used either alone or as a mixture of two or more thereof.
From the standpoints of impact resistance and compatibility with the thermoplastic resin as ingredient (B) in the resin compositions to be obtained according to the invention and from the standpoint of a property balance in the asphalt composition to be obtained according to the invention, the content of the vinylaromatic hydrocarbon in the block copolymer is from 5% by weight to less than 60% by weight, preferably from 10 to 50% by weight, more preferably from 15 to 45% by weight, and the total content of isoprene and 1,3-butadiene is more than 40% by weight to 95% by weight, preferably from 50 to 90% by weight, more preferably from 55 to 85% by weight.
The weight ratio of isoprene to 1,3-butadiene in the block copolymer as ingredient (A) is from 95/5 to 5/95, preferably from 90/10 to 10/90, more preferably from 85/15 to 15/85, from the standpoints of melt viscosity change during molding and impact resistance in the resin compositions and from the standpoint of high-temperature storage stability in the asphalt composition. In the case where a resin composition especially having excellent low-temperature impact resistance is to be obtained or where an asphalt composition especially having excellent low-temperature characteristics is to be obtained, it is recommended that the weight ratio of isoprene to 1,3-butadiene should be from 60/40 to 5/95, preferably from 55/45 to 10/90, more preferably from 50/50 to 15/85.
The vinyl bond amount in the block copolymer (A) as a component in the invention is less than 40% by weight, preferably 35% by weight or lower, more preferably from 30 to 10% by weight. Especially in the resin compositions, it is recommended that the vinyl bond amount should be preferably less than 30% by weight, more preferably from 27 to 10% by weight, from the standpoint of low-temperature impact resistance.
The term vinyl bond amount herein means the proportion of the butadiene and isoprene which have been incorporated in the forms of 1,2-bond and 3,4-bond in the butadiene and isoprene incorporated in the bond forms of 1,2-bond, 3,4-bond, and 1,4-bond in the block copolymer.
For obtaining a resin composition or asphalt composition having satisfactory low-temperature characteristics, it is recommended that the block copolymer to be used in the invention should be one in which the main dispersion peak of tans determined through a viscoelasticity examination and attributable to the copolymer block comprising isoprene and 1,3-butadiene and/or copolymer block comprising isoprene, 1,3-butadiene, and a vinylaromatic hydrocarbon appears at below 0xc2x0 C., preferably below xe2x88x9220xc2x0 C., more preferably below xe2x88x9225xc2x0 C.
In the case where a resin composition having excellent impact resistance is to be obtained in the invention and used for forming a molded article with satisfactory rigidity therefrom or where an asphalt composition having even better high-temperature storage stability is to be obtained in the invention, it is recommended that the proportion of vinylaromatic hydrocarbon polymer blocks incorporated in the block copolymer (A) (referred to as block percentage of the vinylaromatic hydrocarbon) should be regulated to from 50 to 100% by weight, preferably from 50 to 97% by weight, more preferably from 60 to 95% by weight, most preferably from 70 to 92% by weight.
The block percentage of the vinylaromatic hydrocarbon incorporated in a block copolymer can be determined by treating the block copolymer by the method of oxidative decomposition with tert-butyl hydroperoxide with the aid of osmium tetroxide as a catalyst (the method described in I. M. KOLTHOFF, et al., J. Polym. Sci. 1, 429(1946)) to obtain vinylaromatic hydrocarbon polymer block components (provided that the vinylaromatic hydrocarbon polymer block components having an average degree of polymerization of about 30 or lower have been removed) and determining the block percentage from the amount of these polymer components using the following equation.
Block percentage of vinylaromatic hydrocarbon (wt %)=[(weight of vinylaromatic hydrocarbon polymer blocks in the block copolymer)/(weight of all vinylaromatic hydrocarbon in the block copolymer)]xc3x97100 
The block percentage of the vinylaromatic hydrocarbon can be controlled by changing, for example, the weights of the vinylaromatic hydrocarbon, isoprene and 1,3-butadiene or the weight ratio or polymerizability ratio between these ingredients in the step of copolymerizing the vinylaromatic hydrocarbon, isoprene and 1,3-butadiene in the production of the block copolymer (A). Specifically, use can be made of, e.g., a method in which a mixture of the vinylaromatic hydrocarbon, isoprene and 1,3-butadiene is continuously fed to a polymerization system and polymerized and/or a polar compound or randomizing agent is used to copolymerize the vinylaromatic hydrocarbon, isoprene and 1,3-butadiene. Examples of the polar compound or randomizing agent include ethers such as tetrahydrofuran, diethylene glycol dimethyl ether, and diethylene glycol dibutyl ether, amines such as triethylamine and tetramethylethylenediamine, thioethers, phosphines, phosphoramides, alkylbenzenesulfonic acid salts, potassium or sodium alkoxides, and the like. These polar compounds or randomizing agents can be used also for regulating the vinyl bond amount.
The block copolymer (A) in the invention is a block copolymer having at least two polymer blocks mainly comprising a vinylaromatic hydrocarbon and further having at least one copolymer block comprising isoprene and 1,3-butadiene and/or at least one copolymer block comprising isoprene, 1,3-butadiene, and a vinylaromatic hydrocarbon.
Examples of the block copolymer (A) include linear block copolymers represented by the general formulae
(a) Sxe2x80x94(D-S)n
(b) Sxe2x80x94(D-S)nxe2x80x94D
(c) D-(Sxe2x80x94D)n+1
and linear block copolymers or radial block copolymers represented by the following general formulae.
(d) [(Sxe2x80x94D)k]n+1xe2x80x94X
(e) [(Sxe2x80x94D)kxe2x80x94S]n+1xe2x80x94X
(f) [(Dxe2x80x94S)k]n+1xe2x80x94X
(g) [(Dxe2x80x94S)kxe2x80x94D]n+1xe2x80x94X
The block copolymer (A) preferably is a linear block copolymer from the standpoint of obtaining an excellent property balance in the case of obtaining the asphalt composition of the invention.
[In the formulae given above, S represents a polymer block mainly comprising a vinylaromatic hydrocarbon. D represents a copolymer block comprising isoprene and 1,3-butadiene and/or a copolymer block comprising isoprene, 1,3-butadiene, and a vinylaromatic hydrocarbon and having a vinylaromatic hydrocarbon content less than 70% by weight. X represents either a residue of a coupling agent such as, e.g., silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, polyhalogenated hydrocarbon, carboxylic acid ester, or polyvinyl compound or a residue of an initiator such as a polyfunctional organolithium compound. Furthermore, n, k and m are integers of 1 or larger, generally from 1 to 5.)
The polymer block shown above mainly comprising a vinylaromatic hydrocarbon is a block which is a vinylaromatic hydrocarbon homopolymer and/or a copolymer of a vinylaromatic hydrocarbon with 1,3-butadiene and/or isoprene and comprises at least 70% by weight the vinylaromatic hydrocarbon. In the invention, 1,3-butadiene homopolymer segments and/or isoprene homopolymer segments may coexist in the blocks D. Furthermore, a 1,3-butadiene homopolymer block and/or an isoprene homopolymer block may coexist as a block D in the block copolymer as long as the block copolymer has the at least one copolymer block comprising isoprene and 1,3-butadiene and/or at least one copolymer block comprising isoprene, 1,3-butadiene, and a vinylaromatic hydrocarbon as specified in the invention.
In the case where the asphalt composition of the invention is obtained, the block copolymer (A) may be a block copolymer composition comprising:
(A-1) from 10 to 90% by weight, preferably from 20 to 80% by weight, block copolymer having one polymer block mainly comprising a vinylaromatic hydrocarbon and further having one copolymer block comprising isoprene and 1,3-butadiene and/or one copolymer block comprising isoprene, 1,3-butadiene, and a vinylaromatic hydrocarbon; and
(A-2) from 90 to 10% by weight, preferably from 80 to 20% by weight, block copolymer having at least two polymer blocks mainly comprising a vinylaromatic hydrocarbon and further having at least one copolymer block comprising isoprene and 1,3-butadiene and/or at least one copolymer block comprising isoprene, 1,3-butadiene, and a vinylaromatic hydrocarbon. By using this block copolymer composition, an asphalt composition having an excellent balance between softening point and solubility, workability, or high-temperature storage stability can be obtained.
For use in obtaining the asphalt composition of the invention, the block copolymer (A) may have been hydrogenated as long as the excellent effects of the invention can be produced.
The molecular weight of the block copolymer (A) to be used in the invention, in terms of number-average molecular weight measured by GPC and calculated for standard polystyrene, is from 30,000 to 500,000, preferably from 50,000 to 450,000, more preferably from 70,000 to 400,000, from the standpoints of the impact resistance and workability of the resin composition to be obtained or from the standpoints of the softening point, mechanical strength, solubility, workability, etc. of the asphalt composition to be obtained.
In the invention, a terminal-modified block copolymer comprising a polymer chain and, bonded to at least one end thereof, a polar-group-containing group of atoms can be used as the block copolymer (A). Examples of the polar-group-containing group of atoms include groups of atoms containing at least one polar group selected from a hydroxyl group, carboxyl group, carbonyl group, thiocarbonyl group, acid halide group, acid anhydride group, carboxy group, thiocarboxy group, aldehyde group, thioaldehyde group, carboxylic ester group, amide group, sulfo group, sulfonic ester group, phosphate group, phosphoric ester group, amino group, imino group, nitrile group, pyridyl group, quinoline group, epoxy group, thioepoxy group, sulfide group, isocyanate group, isothiocyanate group, halogenosilicon group, alkoxysilicon group, halogenotin group, alkoxytin group, phenyltin group, and the like. The terminal-modified block copolymer is obtained by reacting a compound having any of these polar-group-containing groups of atoms at the time when polymerization for block copolymer production has been terminated. As the compound having a polar-group-containing group of atoms can, for example, be used the terminal modifier described in JP-B-4-39495.
At least one stabilizer selected from 2-[1-(2hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate, 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)4-methylphenyl acrylate and 2,4-bis((octylthio)methyl]-o-cresol may be added as a stabilizer in the invention in an amount of from 0.05 to 3 parts by weight, preferably from 0.1 to 2 parts by weight, per 100 parts by weight of the block copolymer in order to obtain a resin composition having even higher thermal stability during high-temperature molding or in order to obtain an asphalt composition having even higher-thermal stability during high-temperature melting, storage, and application.
At least one phenolic stabilizer such as n-octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionato]methane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene or 2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine can be added in the invention in an amount of from 0.05 to 3 parts by weight per 100 parts by weight of the block copolymer. Furthermore, at least one organic phosphate or organic phosphite stabilizer such as tris(nonylphenyl) phosphite, 2,2-methylenebis(4,6-di-t-butylphenyl) octyl phosphite, 2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy]-N,N-bis[2-[[2,4,8,10-tetrakis(1,1 dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy]ethyl]ethanamine or tris(2,4-di-t-butylphenyl) phosphite can be added in the invention in an amount of from 0.05 to 3 parts by weight per 100 parts by weight of the block copolymer.
The styrene resins which may be used as ingredient (B) in the invention are conjugated diene compound/vinylaromatic compound block copolymer resins having a vinylaromatic compound content of 60% by weight or higher, non-rubber-modified styrene polymers, impact-resistant polystyrene resins (HIPS) obtained by mixing or graft-polymerizing a rubber such as a butadiene rubber, styrene/butadiene rubber, or ethylene/propylene rubber, and rubber-modified styrene resins such as acrylonitrile/butadiene/styrene copolymer resins (ABS) and methacrylic ester/butadiene/styrene copolymer resins (MBS). The non-rubber-modified styrene polymers are polymers of at least one styrene monomer selected from styrene and alkyl-substituted styrenes, styrenes having an alkyl-substituted nucleus, styrenes having a halogen-substituted nucleus, and the like, such as xcex1-methylstyrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, p-methylstyrene, chlorostyrene, bromostyrene, and vinylxylene, and copolymers of at least one member selected from these styrene monomers with at least one other monomer copolymerizable therewith shown below in which the styrene monomer is contained in an amount of 50% by weight or larger, preferably 70% by weight or larger. Examples of the monomer copolymerizable with the styrene monomers include acrylonitrile, acrylic acid and esters thereof (e.g., esters in which the alcohol moiety is an alkyl having 1 to 12 carbon atoms, such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate), methacrylic acid and esters thereof (e.g., esters in which the alcohol moiety is the same as that shown above, such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate), xcex1,xcex2-unsaturated dicarboxylic acids such as fumaric acid, maleic acid, and itaconic acid and monoesters, diesters, anhydrides, and imides of these (e.g., maleic anhydride, maleimide, and the like), and the like. Preferred styrene resins are polystyrene, rubber-modified impact-resistant polystyrenes, styrene/n-butyl acrylate copolymers, styrene/methyl methacrylate copolymers, and the like. These styrene resins can be used alone or as a mixture of two or more thereof. The styrene resin to be used in the invention has a melt flow rate (MFR: 200xc2x0 C., 5-kg load) of preferably from 0.5 to 30 g/10 min, more preferably from 1 to 20 g/10 min.
The polyolefin resins which may be used as ingredient (B) in the invention are not particularly limited as long as these are resins obtained by polymerizing one or more xcex1-olefins, e.g., ethylene, propylene, 1-butene, isobutylene, and 4-methyl-1-pentene. The copolymers may be either random copolymers or block copolymers, and may contain a thermoplastic olefin elastomer such as a copolymer rubber formed from two or more xcex1-olefins or a copolymer of an xcex1-olefin and other monomer(s). Examples of such copolymer rubbers include ethylene/propylene copolymer rubbers (EPR), ethylene/butene copolymer rubbers (EBR), ethylene/hexene copolymer rubbers, ethylene/octene copolymer rubbers, ethylene/propylene/diene copolymer rubbers (EPDM), and the like. Preferred of these are polypropylene and polyethylene which are homopolymers or block polymers. The polyolefin resin in the invention has a melt flow rate (MFR: 230xc2x0 C., 2.16-kg load) of preferably from 0.5 to 60 g/10 min, more preferably from 1 to 20 g/10 min.
Furthermore, the poly(phenylene ether) resins which may be used as ingredient (B) in the invention are polymers or copolymers of 2,6-dimethylphenol or derivatives thereof (e.g., those in which the phenyl group has, bonded thereto, one or more of halogens, alkyl groups having 1 to 7 carbon atoms, phenyl group, haloalkyl groups, aminoalkyl groups, hydrocarbon-oxy groups, and halohydrocarbon-oxy groups). Examples thereof include poly(2,6-dimethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenylene ether), copolymers of 2,6-dimethylphenol and other phenol(s) (e.g.,. 2,3,6trimethylphenol or 2-methyl-6-butylphenol), graft-modified poly(2,6-dimethyl-1,4-phenylene ethers) obtained by graft-polymerizing styrene, xcex1-methylstyrene, an acrylic ester, a methacrylic ester, acrylonitrile, methacrylonitrile, or the like with poly(2,6-dimethyl-1,4-phenylene ether), and the like. These poly(phenylene ether) resins have a reduced viscosity (0.5 g/dL; chloroform solution; measured at 30xc2x0 C.) of generally in the range of from 0.15 to 0.7, preferably from 0.2 to 0.6.
Examples of the asphalt which may be used as ingredient (B) in the invention include ones obtained as by-products of petroleum refining (petroleum asphalts) or as natural products (natural asphalts), ones obtained by mixing these with a petroleum, and the like. The main component of these asphalts is the material called bitumen. Specifically, use can be made of a straight asphalt, semi-blown asphalt, blown asphalt, cutback asphalt to which a tar, pitch, or oil has been added, asphalt emulsion, or the like. These may be used as a mixture thereof. A preferred asphalt for use in the invention is a straight asphalt having a penetration of from 30 to 300, preferably from 40 to 200, more preferably from 45 to 150. In the asphalt composition of the invention, the blending ratio between the block copolymer and the asphalt is from 2/98 to 40/60, preferably from 3/97 to 30/70, more preferably from 3/97 to 20/80.
The hydrogenated block copolymer which may be used as ingredient (C) in the invention is a product of hydrogenation of the block copolymer described above comprising a vinylaromatic hydrocarbon and a conjugated diene. From the standpoint of compatibility with styrene resins and poly(phenylene ether) resins, the degree of hydrogenation thereof is 20% or higher, preferably 30% or higher, more preferably 40% or higher. In the case where a resin composition having even better low-temperature characteristics is obtained, it is recommended that the degree of hydrogenation thereof should be from 20% to less than 70%, preferably from 35% to less than 65%, more preferably from 37 to 60%. From the standpoint of functioning as a compatibilizing agent for styrene resins and/or poly(phenylene ether) resins with polyolefin resins, the hydrogenated block copolymer of ingredient (C) has a vinylaromatic hydrocarbon content of from 10 to 90% by weight, preferably from 20 to 80% by weight, more preferably from 30 to 75% by weight.
The unhydrogenated block copolymer for ingredient (C) can be a block copolymer having the same structure and molecular weight as ingredient (A). However, the conjugated diene is not limited to isoprene and butadiene, and use can be made of butadiene alone, isoprene alone, or another diolefin having a pair of conjugated double bonds, e.g., 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, or 1,3hexadiene. It is recommended that in the unhydrogenated block copolymer, the vinyl bond amount attributable to the conjugated diene compound should be from 20% to less than 75%, preferably from 25 to less than 65%, more preferably from 30 to 60%. The term vinyl bond amount herein means the proportion of the conjugated diene compound which has been incorporated in the forms of 1,2-bond and 3,4-bond in the conjugated diene compound incorporated in the bond forms of 1,2-bond, 3,4-bond, and 1,4-bond in the block copolymer.
The proportion of each component in the resin compositions of the invention is as follows.
In the case of the two-component system (1) described above, the proportion of the block copolymer (A) is from 2 to 40 parts by weight, preferably from 4 to 35 parts by weight, more preferably from 6 to 30 parts by weight, and that of ingredient (B), which is at least one thermoplastic resin selected from styrene resins, polyolefin resins, and poly(phenylene ether) resins, is from 98 to 60 parts by weight, preferably from 95 to 65 parts by weight, more preferably from 93 to 70 parts by weight, from the standpoints of the impact resistance and rigidity of the resin composition to be obtained.
In the case of the three-component system (2) described above, the proportion of the block copolymer (A) is from 2 to 40% by weight, preferably from 4 to 35% by weight, more preferably from 6 to 30% by weight, and that of ingredient (B), which is at least one thermoplastic resin selected from styrene resins, polyolefin resins, and poly(phenylene ether) resins, is from 98 to 60% by weight, preferably from 95 to 65% by weight, more preferably from 93 to 70% by weight. Furthermore, the proportion of the hydrogenated block copolymer of ingredient (C) is from 2 to 30 parts by weight, preferably from 3 to 20 parts by weight, more preferably from 5 to 15 parts by weight, per 100 parts by weight of the sum of ingredients (A) and (B) from the standpoints of compatibilizing effect and rigidity. In the case where one or more styrene resins and/or one or more poly(phenylene ether) resins (referred to as ingredient B1) are used in combination with one or more polyolefin resins (referred to as ingredient B-2) in the resin composition (2), the proportion of ingredient B-1 to ingredient B-2 is 95-5/5-95, preferably 90-10/10-90, more preferably 80-20/20-80, from the standpoint of a balance between rigidity and heat resistance or oil resistance.
The resin compositions of the invention can be produced by any compounding method which has been known. For example, use is made of: a melt kneading method using a general mixing machine such as an open roll mill, intensive mixer, internal mixer, co-kneader, continuous kneading machine equipped with a twin-screw rotor, or extruder; a method in which the ingredients are dissolved or dispersed in a solvent and mixed together and the solvent is then removed with heating; or the like.
Various additives can be incorporated into the resin compositions of the invention according to need. Examples of these additives include additives for general use in plastic compounding, such as, e.g., inorganic reinforcements such as glass fibers, glass beads, silica, calcium carbonate, and talc, organic reinforcements such as organic fibers and coumarone-indene resins, crosslinking agents such as organic peroxides and inorganic peroxides, pigments such as titanium white, carbon black, and iron oxide, dyes, flame retardants, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, other extenders, and mixtures of these.
Methods of mixing for producing the asphalt composition of the invention are not particularly limited. The composition can be prepared through heating, melting, and kneading with, e.g., a melting tank, kneader, Banbury mixer, extruder, or the like optionally together with the various additives mentioned above.
Various additives can be incorporated into the asphalt composition of the invention according to need. Examples of these additives include inorganic fillers such as calcium carbonate, magnesium carbonate, talc, silica, alumina, titanium oxide, glass fibers, and glass beads, organic reinforcements such as organic fibers and coumarone-indene resins, crosslinking agents such as organic peroxides and inorganic peroxides, pigments such as titanium white, carbon black, and iron oxide, dyes, flame retardants, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, softeners/plasticizers such as paraffinic process oils, naphthenic process oils, aromatic process oils, paraffins, organic polysiloxanes, and mineral oils, tackifier resins such as coumarone-indene resins and terpene resins, polyolefin resins such as atactic polypropylene and ethylene/ethyl acrylate copolymers, vinylaromatic-based thermoplastic resins having a low molecular weight, natural rubber, synthetic rubbers such as polyisoprene rubbers, ethylene/propylene rubbers, chloroprene rubbers, acrylic rubbers, isoprene/isobutylene rubbers, and styrene/butadiene block copolymers or styrene/isoprene block copolymers other than those according to the invention, vulcanizing agents such as sulfur, vulcanization aids, other extenders, and mixtures of these. In particular, when the asphalt composition of the invention is for use in road paving, the composition is mixed with an ordinary mineral aggregate such as crushed stones, sand, or slag before use.